Vibration can be a nuisance or at times cause catastrophic consequences including personal injury and damage to property. Vibration occurs in many different forms, and regularly arises out of use of tools, equipment, and machinery common in everyday application. Vibration control and attenuation is important in preventing both injury and property damage. It is also important in preventing damage to structures either housing equipment or machinery, or upon which the equipment or machinery is being used.
Vibration control and attenuation can be accomplished in many different ways. This includes passive control devices, active control devices, and hybrid devices. It is not uncommon for tools, equipment or machinery causing vibrations to utilize dampeners that in many instances are solid structures having a durometer appropriate for absorbing vibration. For example, machinery such as aircraft and motor vehicles have motor mounts connecting an aircraft or motor vehicle motor to the aircraft or motor vehicle structure where the motor mounts contain structures including solid blocks of vibration absorbing material, such as rubber, that will attenuate vibration resulting from the motor operation. These types of vibration control devices are limited in their ability to entirely reduce vibration due to varying degrees of vibrations that occur as a result of variations caused by the oscillations of a tool, equipment and machinery. Further, it is well known that in many applications tools, equipment and machinery have continuing vibration conditions that are not adequately addressed with current dampeners. In addition, hand held tools and firearms exhibit vibrations that are not adequately addressed with current applications, including solid dampening systems. Therefore, it would be an advantage to provide a vibration dampening system that counters or attenuates vibrations in a manner that accounts for variations in the direction and degree of oscillations but does not add significant cost or weight and burden to existing tool, equipment or machinery systems.
Further, vibrations are known to cause injury, especially in applications where individuals control a tool, equipment or machinery that is vibrating during its operation. Injuries include vibration white finger (VWF), also known as hand-arm vibration syndrome (HAVS) or “dead-finger.” This is an injury triggered by continuous use of vibrating machinery. HAVS is a widespread recognized industrial disease affecting tens of thousands of workers. It is a disorder that affects the blood vessels, nerves, muscles and joints of the hand, wrist and arm. Good practice in industrial health and safety management requires that worker vibration exposure is assessed in terms of acceleration, amplitude and duration. For example, using a tool that vibrates slightly for a long time can be as damaging as using a heavily vibrating tool for a short time. Therefore, it is important to develop and implement systems that dampen and attenuate vibration, that addresses heavy vibration and lighter vibration that can occur for longer periods of time.
In physics, dampening is an effect that reduces the amplitude of oscillations in an oscillatory system. Dampening can be achieved in an overdamp, critically damped, under damped and undamped result. The difficulty in addressing dampening of a vibrating system is accounting for variations in oscillations (vibrations) that in many instances change based on the operation of tool, equipment or machinery and associated motor/engine including its associated vibrating systems. Vibration dampening can be resolved through phase shifting occurring when a vibrating system is countered with a system that changes the oscillations in a manner that the oscillations are cancelled through phase differentiation. Therefore, it is desirable to develop and provide an economical system for dampening vibrations that is adaptable to wide application and will provide a safe and stable system for cancelling vibration in a wide range of vibrating systems.
Vibration control is important not only to reduce injury to operators and passengers in the case of vehicles/aircraft applications, but is also important to reduce damage to equipment and machinery, including the surrounding structure of the vibrating source and associated equipment such as control equipment in an aircraft. Further, vibration control is necessary to reduce damage to cargo. In addition, vibration control is important for allowing control of the vibrating system. For example, control of hand held tool or equipment could be greatly increased with adequate vibration control. Without it, hand held equipment can become cumbersome and virtually uncontrollable for its operators. This can relate to simple equipment such as a hand held hammer drill or floor cleaning or polishing equipment that if uncontrolled will be difficult to move due to its inherent vibrations.
In addition, it is important that the points of vibration control not create a weak link in a tool, equipment or machinery. Therefore, it is necessary to have a robust structure, having vibration dampening capability that adequately addresses the problems created by vibration but does not create structural weakness problems. Lastly, vibration may not be necessarily linear but frequently is multi-directional and results in permeation of vibration throughout a system or structure. Therefore, linear shock absorbers and other systems that are adept at reducing vibration in a linear direction are inadequate for multi-directional applications. Therefore, it would be an additional benefit to provide a system capable of vibration dampening in a multi-directional application.